Trailer vehicles can be braked in an electronically open-loop or closed-loop controlled fashion using an electronic brake system (“EBS”). Electronic brake systems are usually used in vehicles, in particular utility vehicles, such as trucks, and have, inter alia, the function of controlling brake cylinders or other brake application devices of a service brake installation of the vehicle at all the axles of the vehicle when a brake pedal is activated. Brakes to which the brake cylinders are assigned respond simultaneously and uniformly. With electronic brake systems it is possible to shorten a braking distance of the vehicle and at the same time achieve uniform wear of brake linings. The electronic brake system can actuate the pneumatically operating brake cylinders or service brake devices electronically. Flow times for a buildup of pressure or reduction in pressure are reduced and reaction times of the brake system are shortened in this context.
Known electronically closed-loop controlled brake systems, cf. Bosch, Kraftfahrtechnisches Taschenbuch [Bosch automotive manual], 26th edition, page 904, include a control device and pressure controlling modules, which are connected in a signal-transmitting fashion to the control device, and to which brake devices of the vehicle are assigned. In this context, it is possible to arrange one or more control units in a decentralized fashion. If an input signal relating to a braking request is present at the control unit, the pneumatic control pressures that are present at a control pressure line, which conducts a redundancy pressure, are shut off in the pressure controlling modules. The electronic control unit determines a brake setpoint pressure as a function of a deceleration request and further vehicle parameters. This brake setpoint pressure is transmitted to the brake controlling modules. The brake controlling modules apply the brake setpoint pressure to the brake cylinders on an axle basis or wheel basis.
For trailer vehicles, trailer control modules are known, cf. Bosch, automotive manual, 26th edition, page 906, that permit the trailer control pressure to be controlled in accordance with the functional requirements of the electronic brake system. A method for operating an electronically controlled pressure medium brake installation is known, for example, from DE 101 56 673 A1.
In addition, both known towing vehicles and known trailer vehicles have light systems for signaling braking processes. Brake lights of the light system of the trailer vehicle can be actuated as brake lights of the towing vehicle. An electrical connection for this purpose can utilize a standardized plug-type connection according to ISO 12098 between the towing vehicle and the trailer vehicle.
In order to inform traffic following the vehicle about the severity of a braking operation, an adaptive brake light, or the modulation of an emergency brake light, is known for towing vehicles. In this case, the control unit of the electronically closed-loop controlled brake installation in the towing vehicle carries out an emergency braking evaluation, wherein available vehicle parameters are evaluated and in response thereto it is decided whether an emergency braking situation is present. This rules out the possibility of hazardous situations arising for the following car traffic as a result of incorrect indication of emergency braking of the towing vehicle. If an emergency braking situation is detected, it is displayed by means of the adaptive brake light or the emergency brake light of the towing vehicle, and the following traffic is correspondingly informed or warned about the severity of the braking operation.
However, if the towing vehicle tows a trailer vehicle, in particular a semitrailer or drawbar trailer, the emergency brake light on the towing vehicle for indicating emergency braking to the following traffic cannot be seen since it is covered by the trailer vehicle. In emergency braking situations of vehicle trains, which have the towing vehicle and at least one trailer vehicle, hazardous traffic situations may therefore occur even if the towing vehicle is equipped with an adaptive brake light. It may not be possible to couple a brake light on the trailer vehicle to the adaptive brake light or the emergency brake light of the towing vehicle since the abovementioned plug-type connection according to ISO 12098 between the towing vehicle and the trailer vehicle does not provide the necessary connection facility.
DE 10 2007 054 189 A1 discloses a brake control module for a trailer vehicle that actuates warning lamps and/or brake lights of a trailer vehicle having this brake control module. For this purpose, the brake control module is actuated by the towing vehicle via a towing vehicle-warning lamp interface provided for this purpose. A disadvantage of this actuation process is that it therefore requires specific interfaces to be provided both on the towing vehicle and on the trailer vehicle, which interfaces do not correspond to the standard. As a result, trailer vehicles that have a brake control module according to DE 10 2007 054 189 A1 are not able to be coupled to towing vehicles with standardized interfaces and operated therewith. Furthermore, although the brake lights of the trailer vehicle are actuated by this known brake control module, additional actuation of an adaptive brake light or of an emergency brake light by this brake control module is not provided and/or does not appear possible without once more expanding the interfaces between the towing vehicle and the trailer vehicle. The following traffic is therefore not informed about an emergency braking operation either.